In the production of video contents such as production of television programs, production of movies, and the like, images are generally taken while the illumination and imaging conditions are adjusted at the location such that the images can be taken at an optimal luminance in accordance with imaging environments, performance of video cameras, and the like. For this purpose, it is necessary to determine in real time whether or not the luminance level of a taken video image meets the intention of a cameraman at the location. For detecting the luminance level of a video image, generally, a method involves displaying a captured image itself on a picture monitor to detect the luminance level, while another method relies on an image analyzed on a waveform monitor described in FIG. 7(b) of Patent Document 1 to detect the luminance level.
Patent Document 1: JP-2004-147005-A